Jaw crushers are utilized in many applications for crushing hard material, such as pieces of rock, ore, etc. A jaw crusher has a movable jaw that cooperates with a stationary jaw. Between the jaws a crushing gap is formed. The size of the crushing gap is often adjustable by means of a hydraulic ram which is connected to the movable jaw via a toggle plate and a toggle beam. Adjustment of the movable jaw position may be carried out to compensate for wear of wear parts and/or to adjust the size of the crushed material. In order to secure that the toggle plate is seated in a proper manner a jaw crusher may be provided with an arrangement that exerts a tensioning force acting to tension the toggle plate against toggle plate seats.
U.S. Pat. No. 4,637,562 discloses a jaw crusher with a toggle plate tensioning device where a compression spring exerts a force acting to tension the toggle plate against its respective toggle seats. U.S. Pat. No. 4,637,562 also discloses a hydraulic mechanism for adjusting the position of the movable jaw.
However, with the design described in U.S. Pat. No. 4,637,562 it may be difficult to secure a proper positioning of the toggle plate due to backlash arising during a crusher operation. Especially, upon presence of un-crushable material in the crusher such backlash may arise.